STP1291

    Determination of 230TH, 234U, 239PU, and 240PU in Soils by ICP-MS Using Flow-Injection Preconcentration

    Published: Jan 1995


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    Abstract

    The US Department of Energy needs improved analytical methods for alpha-emitting radionuclides to support environmental restoration and waste management projects. Inductively coupled plasma-mass spectrometry (ICP-MS) has been used successfully to measure radionuclides with relatively long half-lives; however, ICP-MS used with conventional sample introduction techniques lacks the sensitivity or selectivity to measure shorter-lived radionuclides at levels important for environmental monitoring. New methods were developed for measuring 230Th, 234U, 239Pu, and 240Pu in soils. Samples are dried, ground, and dissolved by fusion. A flow injection (FI) analysis system is used to separate and concentrate the analytes by solid-phase extraction. The FI eluent is pumped directly into the nebulizer of the ICP-MS. The use of FI resulted in greater sensitivity and freedom from interferences when compared with direct aspiration. Detection limits are improved by approximately a factor of 20. The detection limits are approximately 3 Bq/kg (4 ng/kg) for 230Th, 0.6 Bq/kg (3 ng/kg) for 234U, 0.4 Bq/kg (0.2 ng/kg) for 239Pu, and 2 Bq/kg (0.3 ng/kg) for 240Pu. The FI-ICP-MS methods are faster, less labor intensive, and generate less laboratory waste than traditional radiochemical methods. The FI-ICP-MS gives individual results for 239Pu and 240Pu which cannot be resolved by the usual radiochemical method. The accuracy of the methods was verified by analyzing reference soils.

    Keywords:

    thorium-230 determination, uranium-234 determination, plutonium-239 determination, plutonium-240 determination, inductively coupled plasma-mass spectrometry, flow injection


    Author Information:

    Hollenbach, M
    Senior staff scientist, staff scientist, and senior associate scientists, RUST Geotech Inc., US Department of Energy Grand Junction Projects Office, Grand Junction, CO

    Grohs, J
    Senior staff scientist, staff scientist, and senior associate scientists, RUST Geotech Inc., US Department of Energy Grand Junction Projects Office, Grand Junction, CO

    Kroft, M
    EiChrom Industries, Darien, IL

    Mamich, S
    Senior staff scientist, staff scientist, and senior associate scientists, RUST Geotech Inc., US Department of Energy Grand Junction Projects Office, Grand Junction, CO


    Paper ID: STP15983S

    Committee/Subcommittee: C26.07

    DOI: 10.1520/STP15983S


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